1. Field of the Invention
The invention relates to a safety hook, more particularly to a safety hook including a hook body, a latch unit, and a limiting rod extending through a groove in the hook body for abutting against the hook body when the latch unit is undesirably moved from a locked position toward an unlocked position.
2. Description of the Related Art
FIG. 1 illustrates a conventional safety hook 10 that includes an inverted J-shaped hook body 11 that is formed with a hook mouth, a latch unit 12 for locking and unlocking the hook mouth, and a latch locking unit 13 for preventing undesired unlocking of the latch unit 12.
The hook body 11 includes a ring-shaped base segment 110, an arcuate arm segment 111 that extends upwardly from the base segment 110, and a hook end segment 112 that extends from the arcuate arm segment 110 and that cooperates with a front end portion of the base segment 10 to define the hook mouth of the hook body 11.
The latch locking unit 13 includes a generally U-shaped plate 130 pivoted to the hook body 11 so as to be rotatable relative to the hook body 11 about a first axis (A) between restrained and unrestrained positions, a limiting rod 132 that extends through and that is mounted on lateral wings of the U-shaped plate 130, and a first urging member 134. The first urging member 134 provides an urging force for the U-shaped plate 130 to bias the same in a direction about the first axis (A) as shown in the FIG. 1, until the limiting rod 132 abuts against and is thus stopped by the hook body 11.
The latch unit 12 includes a latch member 121 that is pivoted to the hook body 11 so as to be rotatable relative to the hook body 11 about a second axis (B) between locking and unlocking positions, and a second urging member 122. The latch member 121 has a latch arm 123 that engages the hook end segment 112 of the hook body 11 when the latch member 12 is disposed at the locking position, and that is disengaged from the hook end segment 112 of the hook body 11 when the latch member 121 is disposed at the unlocking position. The latch member 121 further has a limiting arm 124 that extends toward the limiting rod 132. The second urging member 122 provides an urging force for the latch member 121 to bias the same in a direction about the first axis (B) as shown in the FIG. 1, until the latch arm 123 abuts against and is thus stopped by the hook end segment 112. The limiting arm 124 has a free end that is disposed above the limiting rod 132 when the latch member 121 is disposed at the locking position and when the latch locking unit 13 is disposed at the restrained position, and that abuts against and is stopped by the limiting rod 132 when the latch member 121 starts moving from the locked position toward the unlocking position and when the latch locking unit 13 is disposed at the restrained position, thereby preventing rotation of the latch member 121 about the second axis (B).
When the safety hook 10 is to be unlocked, if only a pushing force (F) is exerted to move the latch member 121 toward the arcuate arm segment 111 as shown in FIG. 1, since the limiting arm 124 abuts against and is stopped by the limiting rod 132, pivoting operation of the latch arm 123 about the second axis (B) is blocked. Hence, to permit unlocking of the safety hook 10, a second pushing force (E) as shown in FIG. 1 must be exerted to move the U-shaped plate 130 against the urging force of the first urging member 134 to the unrestrained position such that the latch arm 123 is free to rotate about the second axis (B).
Nevertheless, in view of the structure of the safety hook 10, under the situation that when only the pushing force (F) is exerted, the pushing force (F) is transferred to the limiting rod 132 in a downward direction (D) as shown in FIG. 1, which, in turn, is transferred to the lateral wings of the U-shaped plate 130. Since the structure of the portions of the lateral wings of the U-shaped plate 130 on which the limiting rod 132 is mounted is weaker than other portions of the U-shaped plate 130, the structure of the portions of the lateral wings of the U-shaped plate 130 can break when only an undesired pushing force (F) is exerted on the latch arm 123.